No Effect of Carbohydrate-Protein on Cycling Performance and Indices of Recovery

School of Sport and Exercise Sciences, University of Birmingham, Birmingham, United Kingdom.
Medicine and science in sports and exercise (Impact Factor: 3.98). 12/2009; 42(6):1140-8. DOI: 10.1249/MSS.0b013e3181c91f1a
Source: PubMed


The aim of this study was to determine whether adding protein to a CHO beverage would improve late-exercise cycle time-trial performance over CHO alone. Furthermore, we examined the effects of coingesting protein with CHO during exercise on postexercise markers of sarcolemmal disruption and the recovery of muscle function.
In a double-blind, crossover design, 12 trained male cyclists performed 120 min of steady-state (SS) cycling at approximately 55% VO2max followed by a time trial lasting approximately 1 h. At 15-min intervals during SS exercise, participants consumed either a CHO or a CHO + protein (CHO + Pro) beverage (providing 65 g x h(-1) CHO or 65 g x h(-1) CHO plus 19 g x h(-1) protein). Twenty-four hours after the onset of the SS cycle, participants completed a maximum isometric strength test. At rest and 24 h postexercise, a visual analog scale was used to determine lower-limb muscle soreness, and blood samples were obtained for plasma creatine kinase concentration. Dietary control was implemented 24 h before and during the time course of each trial.
Average power output sustained during time trial was similar for CHO and CHO + Pro, with no effect of treatment on the time to complete the time trial (60:13 +/- 1:33 and 60:51 +/- 2:40 (min:s) for CHO and CHO + Pro, respectively). Postexercise isometric strength significantly declined for CHO (15% +/- 3%) and CHO + Pro (11% +/- 3%) compared with baseline (486 +/- 28 N). Plasma creatine kinase concentrations, and visual analog scale soreness significantly increased at 24 h postexercise, with no difference between treatments.
The present findings suggest that CHO + Pro coingestion during exercise does not improve late-exercise time-trial performance, ameliorate markers of sarcolemmal disruption, or enhance the recovery of muscle function at 24 h postexercise over CHO alone.

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Available from: Asker Jeukendrup, Mar 31, 2014
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    • "Consequently, several studies have investigated the proposed acute ergogenic benefits of carbohydrate plus protein ingestion on time trial performance (Fig. 2). However, none of these studies has detected any acute performance-enhancing effects of amino acid or protein ingestion during exercise [71–75]. In short, dietary protein ingestion with carbohydrate during exercise does not improve exercise performance above carbohydrate ingestion alone when ample carbohydrates are ingested. "
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    ABSTRACT: Dietary protein ingestion following exercise increases muscle protein synthesis rates, stimulates net muscle protein accretion, and facilitates the skeletal muscle adaptive response to prolonged exercise training. Furthermore, recent studies show that protein ingestion before and during exercise also increases muscle protein synthesis rates during resistance- and endurance-type exercise. Therefore, protein ingestion before and during prolonged exercise may represent an effective dietary strategy to enhance the skeletal muscle adaptive response to each exercise session by extending the window of opportunity during which the muscle protein synthetic response is facilitated. Protein ingestion during exercise has also been suggested to improve performance capacity acutely. However, recent studies investigating the impact of protein ingestion during exercise on time trial performance, as opposed to time to exhaustion, do not report ergogenic benefits of protein ingestion. Therefore, it is concluded that protein ingestion with carbohydrate during exercise does not further improve exercise performance when compared with the ingestion of ample amounts of carbohydrate only.
    05/2014; 44 Suppl 1(Suppl 1):105-11. DOI:10.1007/s40279-014-0156-z
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    • "There is already a strong body of scientific evidence showing that the simultaneous ingestion of CHO and protein may attenuate muscle damage (Baty et al., 2007; Bird et al., 2006; Cockburn et al., 2008, 2010; Doyle et al., 1993; Luden et al., 2007; Pritchett et al., 2009; Romano-Ely et al., 2006; Samadi et al., 2012; Saunders et al., 2004, 2007, 2009; Skillen et al., 2008; Valentine et al., 2008), suggesting that the combination of these two macronutrients can be a valuable strategy. However, some studies (Breen et al., 2010; Green et al., 2008; White et al., 2008; Wojcik et al., 2001) do no support these findings. The possible reasons for these discrepancies are (i) the inherent inter-individual variability for indirect systemic markers of muscle damage, namely CK (Betts & Williams, 2010), which was the only blood parameter used to assess muscle damage in the four studies that did not find positive results, and (ii) the different exercise protocols applied. "
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    ABSTRACT: Abstract Exhaustive or unaccustomed intense exercise can cause exercise-induced muscle damage (EIMD) and its undesirable consequences may decrease the ability to exercise and to adhere to a training programme. This review briefly summarises the muscle damage process, focusing predominantly on oxidative stress and inflammation as contributing factors, and describes how nutrition may be positively used to recover from EIMD. The combined intake of carbohydrates and proteins and the use of antioxidants and/or anti-inflammatory nutrients within physiological ranges are interventions that may assist the recovery process. Although the works studying food instead of nutritional supplements are very scarce, their results seem to indicate that food might be a favourable option as a recovery strategy. To date, the only tested foods were milk, cherries, blueberries and pomegranate with promising results. Other potential solutions are foods rich in protein, carbohydrates, antioxidants and/or anti-inflammatory nutrients.
    International Journal of Food Sciences and Nutrition 11/2013; 65(2). DOI:10.3109/09637486.2013.849662 · 1.21 Impact Factor
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    • "Recently, a number of studies have proposed that the addition of protein to a CHO solution (CHO-PRO) may further augment exercise performance beyond that of CHO supplementation alone [3-5]. However, evidence of performance enhancement remains equivocal, with others observing no additional benefits [6-10] and even ergolytic effects [11]. The discrepant findings may be methodological and based largely upon both variations in CHO feeding strategies [1-4,12] and caloric content of various protein solutions [3-5]. "
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    ABSTRACT: Background The purpose of this study was to examine the efficacy of introducing a fish protein hydrolysate (PEP) concurrently with carbohydrate (CHO) and whey protein (PRO) on endurance exercise metabolism and performance. Methods In a randomised, double blind crossover design, 12 male volunteers completed an initial familiarisation followed by three experimental trials. The trials consisted of a 90 min cycle task corresponding to 50% of predetermined maximum power output, followed by a 5 km time trial (TT). At 15 min intervals during the 90 min cycle task, participants consumed 180 ml of CHO (67 of maltodextrin), CHO-PRO (53.1 of CHO, 13.6 of whey protein) or CHO-PRO-PEP (53.1 of CHO, 11 of whey protein and 2.4 hydrolyzed marine peptides). Results and conclusions During the 90 min cycle task, the respiratory exchange ratio (RER) in the CHO-PRO condition was significantly higher than CHO (p < 0.001) and CHO-PRO-PEP (p < 0.001). Additionally, mean heart rate for the CHO condition was significantly lower than that for CHO-PRO (p = 0.021). Time-to-complete the 5 km TT was not significantly different between conditions (m ± SD: 456 ± 16, 456 ± 18 and 455 ± 21 sec for CHO, CHO-PRO and CHO-PRO-PEP respectively, p = 0.98). Although the addition of hydrolyzed marine peptides appeared to influence metabolism during endurance exercise in the current study, it did not provide an ergogenic benefit as assessed by 5 km TT performance.
    Journal of the International Society of Sports Nutrition 05/2013; 10(1):29. DOI:10.1186/1550-2783-10-29 · 1.91 Impact Factor
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